I keep thinking of doing something with Solar Power. (Southern UK) The easiest, conceptually would be very basic homemade thermal panels but then there's the problem of how to use the hot (warm) water. That involves plumbing and a special hot tank. Once you've gone for that, you may as well spend more and get the high performance 'tubes' and it gets really expensive - even when you shop around. If you go for the PV solution, then people think in terms of going the whole hog, getting connected to the Grid and selling what you don't use. This seems to be flavour of the month and there are many very sexy looking packages, which are being sold quite hard - so someone's making a lot of money out of them. I was thinking about a much simpler (hi tech / lo tech) system, involving PVs on the roof, no fancy plumbing; just a suitable, low voltage, immersion heater in the existing hot tank. At around £1k for 200W, with no regulation or fancy control needed, you're talking about a payback time of less than 10 years (less if you could only get a cheaper source of PV panels), it would sound to me to be very DIY manageable. Can anyone think of any serious snags? I can't think that a 200W heater would ever produce an embarrassing amount of hot water- and it could always be turned off! PVs don't freeze and a few metres of thick cable would be very easy to run. It seems so obvious???